Table 2.

The incidence and risk of COPD in the hospital-based cohort

	Normal serum urate				Hyperuricaemia
	New COPD cases	Person-year	Incidence (/1000 person-years)	RR	New COPD cases	Person-year	Incidence (/1000 person-years)	RR	P value
Original data	22	2474.04	8.89	Ref	15	672.80	22.29	2.51 (1.21 to 5.06)	0.009
PSM	9	1149.39	7.83	Ref	15	672.80	22.29	2.85 (1.17 to 7.38)	0.013
IPTW	27	3087.93	8.74	Ref	78	3287.36	23.73	2.71 (1.73 to 4.37)	<0.001

COPD, chronic obstructive pulmonary disease; IPTW, inverse probability of treatment weighting; PSM, propensity score matching; RR, rate ratio.